Forget national procurement, we need global procurement to fix the world

For a long time the talk in the UK public sector has been about how the government can use its £175 billion more effectively. And one method of doing this is by pooling money, working together and eliminating duplication.
But I'm not sure doing this on a national basis will be enough to solve the world's really big problems.
Take climate change for example. (Most) governments around the world will be working on projects, taking large chunks of their procurement budget to invest in innovative products and services with suppliers to tackle global warming. There appears to be a desire in the UK government for "green technology" to drive the country's economy in the future, so developing domestic suppliers makes sense to achieve this.
But what could be achieved if governments pooled their procurement spend in global competition? A larger spend volume and true global competition, unaffected by the spectre of protectionism, must be a more effective way of investing.
Space travel could be another area that could benefit. Last week the US said it would need an extra $3 billion to achieve its future goals in space. Instead, why don't we all combine our procurement budgets to build rockets, space stations and moon bases?
This obviously ignores some fundamental questions, such as who could be trusted to do the procurement, what procurement policies would be followed and how to deal with the petty jealousies of international politics.
But in two areas where all nations are working toward the same goal - the continuation of the human race - surely it makes sense for everyone to chip in and work together.